   [downstream :- NodeNeighborsSchema]
   (/ 1 (+ 1 (count downstream))))
 
+;; TODO: fix function signature, different from every other 'receive-msg fn!
 (s/defn receive-msg-new-subscription :- [MessageEnvelopeSchema]
   "Forward the 'subscription to every :downstream node, duplicating
   the forwarded 'subscription to :connection-redundancy :downstream

  subscribing, and a 'node, forward subscription requests
  from 'node.

  Return 'world with new messages."
  [world :- WorldSchema
   new-node-contact-address :- NodeContactAddressSchema
   contact-node-address :- NodeContactAddressSchema]

  'envelope-id. Either accept the subscription into :downstream, or
  forward it to a :downstream node.

  Return a vector matching 'CommUpdateSchema.

  [1] 2.2.1 Subscription: Algorithm 2"
  [logging-config
   {:keys [downstream] :as node} :- NetworkedNodeSchema
   subscriber-contact-address :- NodeContactAddressSchema
